Switchboard for electric circuits



. 2 Sheets-Sheet 1. A. L. ROHRBR. SWITCHBCARD FOR ELECTRIC CIRCUITS. No. 496,901. Patented May 9,1893.

O. F1919@ i i! (No Model.)

WITNESSES 501W. n.7 @u

2 sheets-sheet 2. A. L. ROHRER. SWI'ICIIBCARD PCR ELECTRIC CIRCUITS.

(No Model.)

No. 496,901, Patented May 9,1893.

WWNESSEE.- INJENTDFV THE NORRIS PETERS C0. FMOYULTHO, WSHYNGYON. C.

UNITED STATES PATENT OFFICE.

ALBERT L. ROHRER, OF LYNN, MASSACHUSETTS, ASSIGNOR TO THE THOMSON-HOUSTON ELECTRIC COMPANY, OF CONNECTICUT.

SWITCHBOARD FOR ELECTRIC CIRCUITS.

SPECIFICATION forming part of Letters Patent N o. 496,901, dated May 9, 1893. Application filed June 20, 1892. Serial IIa-137,270. (No model.)

ToraZZ whom t may concern.-

Be it known that I, ALBERT L. ROHEER, a citizen of the United States, residing at Lynn, county of Essex, State of Massachusetts, have invented a certain new and useful Improvement in Switchboards for Electric Circuits, of which the following is a specification.

My invention relates to switch boards` for electric circuits, and its object is to render it impossible for the operator or any other person to obtain a shock by accidentally touching the metal in circuit. This is accomplished by sinking the xed contact plates below the surface of the insulating material of which the switch board is composed, and by insulating the movable contact plates from the handle .and from each other, as hereinafter pointed out.

In the drawings, Figure l is a front elevation 0f a switch board embodying my invention. Fig. 2 is a rear elevation oi' a portion thereof, and Fig. 3 is a sectional elevation on an enlarged scale.

The front supporting plate A is composed of slate or some other suitable insulating material. Fastened to the rear of this plate are one or more rows of brackets B, having curved arms b and spring clip contact plates b. The curved arms project alternately in opposite directions, the alternate arms, or those projecting in the same direction being united by rods C, C', said rods running parallel with each other. At one end of each rod, the bracket to which it is attached is also connected as by rods d, d with a binding post D, D. The rods thus constitute terminals for the supply mains from the dynamo, which are connected with said posts. Running transversely to the rods C are strips E, E', supported on studs F, and serving as circuit conductors. The studs are arranged in rows parallel with the bracket B and each stud has a spring clip contact f, which lies in the same vertical line as the contact plate b' on the adjacent bracket B, and is supported by a leg f resting on the strip E or E. The contact plates b and f project outwardly in slots a in the switch board A, but do not extend through to the outer surface thereof, as clearly shown in Fig. 3. The operatoris therefore inno danger of touching them, should he place his hand upon the switch board.

Near the row of brackets B are mount-ed upon studs G the double knife switches H. Only one of them is shown, but it is to be understood that one is providedfor every pair of strips E, E', and when two sets of rods C, C are used, the switches are mounted between the rows, as shown, and are provided with opposite contact blades h, h', so that by reversing the position of the switch it will connect the second set of rods with the strips E, E', as indicated in dotted lines in Fig. 3. The contact blades are carefully insulated from the frame h2 and from each other; and the handle h3 is also insulated from the frame. With this construction, when the switch is closed, the only part of it in the circuit is the inner pair of contact blades. This renders it difficult to touch the active part of the switch, since the outer blades if accidentally struck by the operator give him no shock. It is therefore evident that it is impossible to obtain a shock from aswitch board constructed in accordance with my invention, unless a deliberate effort is made to touch the metal in circuit, by reaching under the handle of the switch, or into the slots a.

IVhat I claim as new, and desire to secure by Letters Patent, is-

l. A switch board consisting of an insulating supporting plate containing rows of slots, brackets secured to the rear of said plate, having contacts projecting` into but not through said slots, and provided with curved arms, and rods connecting alternate arms and serving as terminals for the supply mains, substantially as described.

2. The combination with a switch board having its fixed contacts arrangedin slots below the surface of the insulating supporting plate, of a pivoted frame carrying contact blades insulated therefrom,said blades being adapted to enter said slots, substantially as set forth.

3. The combination with a switch board having two sets of supply main terminals, of circuit conductors arranged transversely thereto, said terminals and conductors hav ing contacts arranged in slots below the surface of theinsulating supporting plate, and al dynamo terminals arranged below the surface of an insulating plate provided with openings, of pivoted switch-blades mounted lon opposite sides of an operating handle, insulated there- `from and from each other, and adapted to connect either of said dynamo terminals to the work circuit through said openings in said insulating plate.

6. The combination with a switchboard having the generator and Work circuit terminals located below the surface of an insulating plate, of an insulated pivoted switch-blade adapted to connect said terminals by its insertion through slots in said plate.

7. In an electric switch having the terminals from the supplying and supplied circuits brought in proximity and arranged below the surface of an insulating guard, asWitch-blade adapted to connect said terminals mounted upon but insulated from an operating handle pivoted without said guard.

In witness whereof I have hereto set my hand this 18th day of June, 1892.

ALBERT L. ROHRER.

Witnesses:

JOHN W. GIBBONEY, DUGALD` McKILLoP. 

